1. Field of the Invention
The present invention relates to a holography imaging apparatus for recording three-dimensional information of an object, and a holography display apparatus for reading out the three-dimensional information of an object from the holography imaging apparatus and displaying a three-dimensional image of the object.
2. Related Background Art
Holography has received considerable attention as a technique for displaying a three-dimensional image of an object, a. The holography technique includes a holography imaging technique for recording three-dimensional information of an object, and a holography display technique for reading out the three-dimensional information of an object recorded by the holography imaging technique and displaying the three-dimensional image of the object.
The conventional holography technique is designed based on the premises that the imaging device has a high resolution upon holography imaging, and most of holography imaging apparatuses use a high-resolution photography dryplate or thermoplastic as imaging devices.
Since such imaging technique is basically a high-level photography technique because of the high resolution, holography imaging labor intensive. In view of this problem, the holography techniques using a CCD camera as a relatively low-resolution imaging device are proposed in "Sato et. al., Journal of Television Society, Vol. 45, No. 7, pp. 873-875 (1991)" (hereafter referred to as prior art 1) and "N. Hashimoto et. al., SPIE, Vol. 1461, Practical Holography V (1991), pp. 291-302" (hereafter referred to as prior art 2).
Prior art 1 corresponds to an example of a Fresnel type holography technique which does not use any lenses that are normally used in the holography imaging technique. In the holography imaging technique disclosed in prior art 2, an imaging lens is used so that the spatial resolution of a real image matches that of an imaging device, and a diaphragm is arranged immediately before the position of the object space of the imaging lens.
Interference fringes bearing both the distance information in the optical axis direction and the position information in a direction perpendicular to the optical axis are sensed, and an image to be reconstructed is read out from the interference fringes.
When holography imaging apparatuses of prior arts 1 and 2 are adopted, since the spatial resolution of a CCD is about 10 .mu.m in general, the angle object light and reference light make must fall within the range from 2.degree. to 3.degree.. If the angle object light and reference light make becomes large, the spacing between adjacent interference fringes becomes smaller than the resolution of the imaging device and, hence, the interference fringes cannot be sensed with high contrast.
In the holography imaging apparatuses of prior arts 1 and 2, the pixel pitch and pixel size of the CCD as the imaging device are different from those of a spatial modulation device used in image reconstruction, and the optical system upon holography imaging is different from that upon reconstruction. As a consequence, the enlargement factor of the reconstructed display image essentially varies depending on the position.